Estimation of CMOD in Concrete using Optical Fiber Sensors

Structural Health Monitoring of Concrete plays an important role in ensuring the safety of civil structures.Cracks in civil structures arise due to exposure to natural hazards, corrosion, overload etc.The width of the crack is measured either as crack tip opening displacement (CTOD) or crack mouth opening displacement (CMOD).It is easier to measure CMOD, as CTOD is related to material microstructure.Optical fiber sensors such as plastic optical fibers(POF) and fibre bragg gratings (FBGs) currently find wide application in civil engineering due to several attractive advantges they offer.This work lucidly presents the methodology of estimation of crack width in three point bend specimens of plain concrete using both plastic optic fibers and fiber bragg gratings. The work also presents the details of instrumentation developed and used for testing .The work also compares the results of the techniques employed and serves as a first guide for choosing the method.